Doing a self-audit like this is actually an amazing idea. I consider and re-consider my choices every once in a while, but sitting down and doing an end-to-end write-up would put me a lot more at ease.
Like you, I also considered the implications of mixing TOTP into KeePass, but eventually landed on going all-in on the one database. It does mean raising the bar for keeping it secure, but it was already very high to begin with.
One thing I have considered is combining this all-in-one approach with an additional keyfile, which I could then share OOB to devices, effectively adding a second factor. I like the idea of using Yubikey or similar, but the fear of locking myself out is too great.
Like you, I also considered the implications of mixing TOTP into KeePass, but eventually landed on going all-in on the one database. It does mean raising the bar for keeping it secure, but it was already very high to begin with.
One thing I have considered is combining this all-in-one approach with an additional keyfile, which I could then share OOB to devices, effectively adding a second factor. I like the idea of using Yubikey or similar, but the fear of locking myself out is too great.